/* SPDX-License-Identifier: GPL-2.0 */
/*  linux/include/linux/clockchips.h
 *
 *  This file contains the structure definitions for clockchips.
 *
 *  If you are not a clockchip, or the time of day code, you should
 *  not be including this file!
 */
#ifndef DEVICES_CLOCKCHIPS_H
#define DEVICES_CLOCKCHIPS_H

#include <seminix/cpumask.h>
#include <seminix/ktime.h>
#include <devices/clocksource.h>

/*
 * Possible states of a clock event device.
 *
 * DETACHED:	Device is not used by clockevents core. Initial state or can be
 *		reached from SHUTDOWN.
 * SHUTDOWN:	Device is powered-off. Can be reached from PERIODIC or ONESHOT.
 * PERIODIC:	Device is programmed to generate events periodically. Can be
 *		reached from DETACHED or SHUTDOWN.
 * ONESHOT:	Device is programmed to generate event only once. Can be reached
 *		from DETACHED or SHUTDOWN.
 * ONESHOT_STOPPED: Device was programmed in ONESHOT mode and is temporarily
 *		    stopped.
 */
enum clock_event_state {
    CLOCK_EVT_STATE_DETACHED,
    CLOCK_EVT_STATE_SHUTDOWN,
    CLOCK_EVT_STATE_PERIODIC,
    CLOCK_EVT_STATE_ONESHOT,
    CLOCK_EVT_STATE_ONESHOT_STOPPED,
};

/*
 * Clock event features
 */
#define CLOCK_EVT_FEAT_PERIODIC     0x000001
#define CLOCK_EVT_FEAT_ONESHOT      0x000002
#define CLOCK_EVT_FEAT_KTIME        0x000004

/*
 * x86(64) specific (mis)features:
 *
 * - Clockevent source stops in C3 State and needs broadcast support.
 * - Local APIC timer is used as a dummy device.
 */
#define CLOCK_EVT_FEAT_C3STOP       0x000008
#define CLOCK_EVT_FEAT_DUMMY        0x000010

/*
 * Core shall set the interrupt affinity dynamically in broadcast mode
 */
#define CLOCK_EVT_FEAT_DYNIRQ       0x000020
#define CLOCK_EVT_FEAT_PERCPU       0x000040

/*
 * Clockevent device is based on a hrtimer for broadcast
 */
#define CLOCK_EVT_FEAT_HRTIMER      0x000080

/**
 * struct clock_event_device - clock event device descriptor
 * @event_handler:	Assigned by the framework to be called by the low
 *			level handler of the event source
 * @set_next_event:	set next event function using a clocksource delta
 * @set_next_ktime:	set next event function using a direct ktime value
 * @next_event:		local storage for the next event in oneshot mode
 * @max_delta_ns:	maximum delta value in ns
 * @min_delta_ns:	minimum delta value in ns
 * @mult:		nanosecond to cycles multiplier
 * @shift:		nanoseconds to cycles divisor (power of two)
 * @state_use_accessors:current state of the device, assigned by the core code
 * @features:		features
 * @retries:		number of forced programming retries
 * @set_state_periodic:	switch state to periodic
 * @set_state_oneshot:	switch state to oneshot
 * @set_state_oneshot_stopped: switch state to oneshot_stopped
 * @set_state_shutdown:	switch state to shutdown
 * @tick_resume:	resume clkevt device
 * @broadcast:		function to broadcast events
 * @min_delta_ticks:	minimum delta value in ticks stored for reconfiguration
 * @max_delta_ticks:	maximum delta value in ticks stored for reconfiguration
 * @name:		ptr to clock event name
 * @rating:		variable to rate clock event devices
 * @irq:		IRQ number (only for non CPU local devices)
 * @cpumask:		cpumask to indicate for which CPUs this device works
 * @list:		list head for the management code
 */
struct clock_event_device {
    void			(*event_handler)(struct clock_event_device *);
    int			(*set_next_event)(u64 evt, struct clock_event_device *);
    int			(*set_next_ktime)(ktime_t expires, struct clock_event_device *);
    ktime_t			next_event;
    u64			max_delta_ns;
    u64			min_delta_ns;
    u32			mult;
    u32			shift;
    enum clock_event_state	state_use_accessors;
    unsigned int        features;
    unsigned long       retries;

    int			(*set_state_periodic)(struct clock_event_device *);
    int			(*set_state_oneshot)(struct clock_event_device *);
    int			(*set_state_oneshot_stopped)(struct clock_event_device *);
    int			(*set_state_shutdown)(struct clock_event_device *);
    int			(*tick_resume)(struct clock_event_device *);

    void			(*broadcast)(const struct cpumask *mask);
    void			(*suspend)(struct clock_event_device *);
    void			(*resume)(struct clock_event_device *);
    unsigned long       min_delta_ticks;
    unsigned long       max_delta_ticks;

    const char		*name;
    int			rating;
    int			irq;

    const struct cpumask	*cpumask;
    struct list_head	list;
} ____cacheline_aligned;

/* Helpers to verify state of a clockevent device */
static inline bool clockevent_state_detached(struct clock_event_device *dev)
{
    return dev->state_use_accessors == CLOCK_EVT_STATE_DETACHED;
}

static inline bool clockevent_state_shutdown(struct clock_event_device *dev)
{
    return dev->state_use_accessors == CLOCK_EVT_STATE_SHUTDOWN;
}

static inline bool clockevent_state_periodic(struct clock_event_device *dev)
{
    return dev->state_use_accessors == CLOCK_EVT_STATE_PERIODIC;
}

static inline bool clockevent_state_oneshot(struct clock_event_device *dev)
{
    return dev->state_use_accessors == CLOCK_EVT_STATE_ONESHOT;
}

static inline bool clockevent_state_oneshot_stopped(struct clock_event_device *dev)
{
    return dev->state_use_accessors == CLOCK_EVT_STATE_ONESHOT_STOPPED;
}

static inline void
clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 maxsec)
{
    return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC, freq, maxsec);
}

/*
 * Calculate a multiplication factor for scaled math, which is used to convert
 * nanoseconds based values to clock ticks:
 *
 * clock_ticks = (nanoseconds * factor) >> shift.
 *
 * div_sc is the rearranged equation to calculate a factor from a given clock
 * ticks / nanoseconds ratio:
 *
 * factor = (clock_ticks << shift) / nanoseconds
 */
static inline u64
div_sc(u64 ticks, u64 nsec, int shift)
{
    u64 tmp = ((u64)ticks) << shift;

    do_div(tmp, nsec);

    return (u64) tmp;
}

/* Clock event layer functions */
extern u64 clockevent_delta2ns(u64 latch, struct clock_event_device *evt);
extern void clockevents_register_device(struct clock_event_device *dev);
extern void clockevents_config_and_register(struct clock_event_device *dev,
                        u32 freq, u64 min_delta,
                        u64 max_delta);
extern int clockevents_update_freq(struct clock_event_device *ce, u32 freq);

extern void clockevents_suspend(void);
extern void clockevents_resume(void);

#endif /* !DEVICES_CLOCKCHIPS_H */
